Catalytic olefin metathesis has transformed chemical synthesis and offers exceptionally efficient pathways for synthesis of alkenes. In the last several years sterically demanding phenoxide ligands have been employed to make Mo- and W-based MAP (MonoAlkoxide Pyrrolide) catalysts for olefin metathesis reactions. One of the first was OBr2Bitet, an enantiomerically pure monophenoxide ligand that yielded diastereomeric mixtures of MAP catalysts (R′═H or Me) for enantioselective ring-opening/cross-metathesis reactions (Ibrahem, I; Yu, M.; Schrock, R. R.; Hoveyda, A. H. J. Am. Chem. Soc. 2009, 131, 3844).

In the process, it was found that the reaction was not only enantioselective but also Z-selective. The search for other suitable sterically demanding phenoxides led to terphenoxides such as O-2,6-(2,4,6-i-Pr3C6H2)2C6H3 (OHIPT)(Stanciu, C.; Olmstead, M. M.; Phillips, A. D.; Stender, M.; Power, P. P. Eur. J. Inorg. Chem. 2003, 3495) and O-2,6-Mesityl2C6H3 (OHMT) (Dickie, D. A.; MacIntosh, I. S.; Ino, D. D.; He, Q.; Labeodan, O. A.; Jennings, M. C.; Schatte, G.; Walsby, C. J.; Clyburne, J. A. C. Can. J. Chem. 2008, 86, 20), which were employed to produce Z-selective catalysts for ROMP ((a) Flook, M. M.; Jiang, A. J.; Schrock, R. R.; Müller, P.; Hoveyda, A. H. J. Am. Chem. Soc. 2009, 131, 7962. (b) Flook, M. M.; Gerber, L. C. H.; Debelouchina, G. T.; Schrock, R. R. Macromolecules 2010, 43, 7515) and homocoupling of terminal olefins ((a) Jiang, A. J.; Zhao, Y.; Schrock, R. R.; Hoveyda, A. H. J. Am. Chem. Soc. 2009, 131, 16630. (b) Marinescu, S. C.; Schrock, R. R.; Müller, P.; Takase, M. K.; Hoveyda, A. H. Organometallics 2011, 30, 1780). Decafluoroterphenoxide (O-2,6-(C6F5)2C6H3= ODFT) has also been added to the list of 2,6-terphenoxides (Yuan, J.; Schrock, R. R.; Müller, P.; Axtell, J. C.; Dobereiner, G. E. Organometallics 2012, 31, 4650). Recently it also has been possible to make bisaryloxide complexes that are especially efficient in certain stereoselective reactions, one example being Mo(NC6F5)(CHCMe2Ph)(OF2Bitet)2, where OF2Bitet is a fluorinated relative of OBr2Bitet (Wang, C.; Haeflher, F.; Schrock, R. R.; Hoveyda, A. H. Angew. Chem. Int. Ed. 2013, 52, 1939). Despite all the development, there remains a need for olefin metathesis catalysts and methods for highly selective and efficient synthesis of Z alkenes.